The instant invention relates to burners and methods of using burners for heating and melting an oxidizable material.
Various burners and methods are known in this art for heating and melting oxidizable materials such as aluminum. One such method is described in U.S. Pat. No. 5,563,903 (hereby incorporated by reference), that describes a process where a layer of non-oxidizing gas is injected between the flame and the aluminum being melted. The non-oxidizing gases include a variety of inert gases or fuels.
EP Patent No. 0748982 (hereby incorporated by reference), describes a process where the burner used to melt the aluminum is allowed to run at sub-stoichiometry to create a reducing atmosphere above the aluminum. The remaining oxidant required for combustion is injected through a separate stream above the burner.
The primary concern associated with combustion equipment used in processes such as aluminum melting or recycling is the metal yield. Aluminum is easily oxidized, and the oxidation process is accelerated at elevated temperatures found in a furnace or melter. Aluminum metal loss due to oxidation is so expensive that furnace operators often operate burners used to heat the furnace in a fuel-rich manner in order to minimize free oxygen found in the furnace.
There is a need in this art for burners and methods for heating materials such as aluminum that minimizes oxidation of such materials thereby increasing the material yield.